Typographic printing-plate



.I`-. MURRAY.

TYPOGRAPHIC PRINTING PLATE.

APPLICATION HLED AuG.15.1921.

1,396,653. Patented Nov. s, 1921.

FIG. 2. FIG. 5.

/NVENTO' UNITED STATES PATENT FFlCE.

JOHN MURRAY, OF LONDON, ENGLAND.

TYPOGRAPHIC PRINTING-PLATE.

Application led August 15, 1921. Serial No. 492,488.

To all whom it ma concern:

Be it known that JOHN MURRAY, a subject of the King of Great Britain andIreland, and a resident of London, England, engineer, have inventedcertain new and useful Typographic Printing-Plates, (for which I havefiled application in England application No. 12692,dated May 7 1920,) ofwhich the following is the specification.

In the preparation of printing surfaces for rotary machines the platesare usually cast in curved casting boxes and bored out to fit thesurface of the cylinder, or they are machined to size While flat,and'are then bent to the desired curvature.

The degree of accuracy attained by either method is insuflicient forgood work and the correction of the defects entails much loss of time.

The invention has for its object to provide a form of plate and adaptthe cylinder to receive it in such wise that the disabilities ofexisting methods are largely or Wholly obviated.

According to the invention the plate, the printing surface of which maybe formed in any desired manner, is initially curved as regards itsouter surface to the radius of the printing surface of the cylinder uponwhich it is mounted while its inner surface is flat or substantially so,that is to say, is

is cut a series of grooves the bottoms of which are coaxial with thecurvature of the outer surface.` The grooves are of such depth and widthas while removing surplus meta-l, to leave the plate of adequatestrength, the upstanding portions between the grooves acting as buttresswebs and materially assisting to this end.

In the surface of the printing cylinder circumferential groovescounterpart tothe upstanding plate are formed. Thus the coacting`grooves and projections or ribs on plate and cyllnder, form definiteand exact locating means in a longitudinal direction, while accuracy ofradial position, depending as it does upon the accuracy readilyattainable in cylindrical surfaces, is assured.

The plates are secured upon the c linder by usual or any convenientmeans. F or example, buttress strips having undercut edges under whichthe beveled edges of the plates engage and which are lodged intransverse grooves in the cylinder may be provided.

An example of the carrying out of the invention is shown on anaccompanying sheet of explanatory drawings in which Figure l, is asectional end elevation of the lmproved plate and part of a cylinder,Fig. 2 a plan and Fig. 3 a transverse section thereof.

As shown in the drawings, the improved plate, the printing surface ofwhich may be formed in any desired manner, is initially curved asregards its outer surface A to the radius of the printing surface of thecylinder B upon which it is mounted, while its inner surface C is flat.Upon the inner surface of the plate is cut a series of grooves, thebottoms D of which are coaxial with the curvature of the outer surface Aand of equal radius to that of the surface of the cylinder B. rlhegrooves are of such depth and width as to lighten the plate veryconsiderably, but at the same time leave in the webs between the groovesadequate material for strength and stiffness of the plate.

j In the surface of the cylinder B are formed circumferentiali grooves Ecounterpart to the ribs left projecting beneath the plate. Thesecoacting parts on cylinder and plate form definite and exactlongitudinal locating means and accuracy of radial positioning dependingas it does upon the ac- `curacy readily attainable in cylindricalsurfaces, is also assured.

What I claim is A typographie printing plate and cylinder therefor, theplate being curved on its outer surface to the radius of the printingsurface and initially fiat or substantially so on its inner surface andhaving in its inner surface a series of grooves the bottoms of which arecurved to the radius of the surface of the cylinder and the cylinderhaving in it a series of circumferential grooves counterpart to the ribsin the inner surface of the plate, as set forth.

In testimony whereof I have signed my name to this specification.

JOHN MURRAY.

